In a heated “mother of all derbies” that prompted crowd trouble before the game and flares in the stadium, Robert Lewandowski and Felipe Santana scored either side of half-time to lift Dortmund to 29 points, one ahead of Bayern Munich who travel to Mainz today.
Borussia Moenchengladbach are in second place, also on 29, after beating Cologne 3-0 away on Friday.
Hertha Berlin and Bayer Leverkusen drew 3-3.